Dynamic mounting mechanism for an exoskeleton

ABSTRACT

The present invention is directed to the affixion of an exoskeleton device that can include multiple rotational degrees of freedom in its attachment mechanism to approximate linear motion orthogonal to the person&#39;s line of action. The present invention can include one or more additional, non-parallel degrees of freedom. The present invention provides a sliding mechanism for adjusting the exoskeleton mating point along the user&#39;s body.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a continuation of U.S. patent applicationSer. No. 16/365,024, filed on Mar. 26, 2019, which claims priority toand claims the benefit of earlier filed U.S. Provisional PatentApplication No. 62/648,576, filed on Mar. 27, 2018, the entire contentsof each of the foregoing are incorporated herein by reference.

GOVERNMENT SUPPORT

This invention was made with government support under W911QY-16-C-0072from the United States Army.

BACKGROUND

The invention relates generally to an exoskeleton, which is an externalaugmentative device worn by a person to enhance their motor functions.This augmentation can come from applying a force which is complementaryto the user's intended motion. The applied force can be used to increasethe user's natural strength by means of adding an additional force inseries to the natural movement. The applied force can also be used toincrease endurance through minimizing the user's effort to complete atask. As the exoskeleton applies a portion of the required force tocomplete a task, the metabolic cost to the user is reduced, increasingtheir endurance at said task. Exoskeletons can also increase mobility byincreasing the strength and/or frequency of the user's motion. Whencoupled with the added endurance, an assistive exoskeleton's enhancedstrength allows a user to complete a motion for longer periods of timeat strengths beyond the capabilities they would have withoutaugmentation. For example, by applying assistive force to the normalgait cycle, the frequency of the gait and distance covered during theinitial swing phase of the gait can be increased. This augmentation of afundamental human movement can result in a greater distance traveledover time, at a lower relative metabolic cost to the user.

Exoskeletons can be considered passive or active depending how theyapply their force, and their reliance on energy storage. Passiveexoskeletons do not require an energy source, such as a battery. Activedevices require an energy source to power electronics and usuallyinclude force/power applying actuators. The exoskeleton functions byapplying its active or passive augmentation through parallel structuresto the user's skeletal system. If the exoskeleton does not act inparallel with the user's innate motility systems, it will loseefficiency, and possibly even resist the user's force.

It is also ideal for the parallel structures to be designed in such away that does not inhibit the user's natural range of motion. Anyimpingement of the user's natural abilities offsets the potentialbenefits of augmentation, and additionally correlates to lower usercomfort. Reducing the user's range of motion also impedes their abilityto perform normal tasks, limiting the use cases for the exoskeleton.Having rigid limits or mis-alignment contrary to the user's range ofmotion creates shear between the person and the mechanical structure.Any user attempts to extend beyond the limited range of motion imposedby the exoskeleton will result in mechanical interference between theexoskeleton mounting bodies and the user's skin, greatly decreasing usercomfort and resulting performance.

In order to enhance the user's intended motion, the exoskeleton mustmove complimentary to the user's musculoskeletal system. Any unintendeddeviations from the user's natural movements can result incounterapplication of augmentation, and an additional loss ofeffectiveness. To this end, it is desirable for the system to be rigidlyaffixed to the user's musculoskeletal system in order to maximize thetransmission of force to the ground, while not being so rigid as torestrict their usual range of motion.

Effective exoskeleton design is highly reliant on proper alignment ofhuman and exoskeleton joints. Misalignment of internal human joints andexternal robotic joints results in shearing between the mating surfacebetween the human and exoskeleton. Any amount of surface shear in themating interface will likely create user discomfort as the shear leadsto inadequate pressure dispersion. This shear can also put an unevenload on the exoskeleton system, creating inefficiencies in thetransmission of force to the user. Additionally, the shearing can leadto increased movement of the exoskeleton with respect to the body of theuser. In all cases, misalignments between the line of actions of thehuman and exoskeleton will decrease efficiency and increase userdiscomfort.

By using a single degree of freedom (DOF) joint, alignment can beaccomplished with rigid fixturing of the human to the exoskeleton. Rigidfixturing initially creates the alignment required between the human androbotic joints to avoid shear. A rigid assembly, however, createsadditional static misalignments though the difficulty in accepting usersof differing size. While assumptions can be made to fit the majority ofusers, this limits the ability of the exoskeleton to be perfectlyaligned with all users. The general deviation in length of the lower legbones can be significant enough to create mechanical devicemis-alignment across a population of users. In an attempt to minimizethis affect, each time the user dons the exoskeleton, they may adjustthe system to the optimal position to avoid an inefficient anduncomfortable session.

An additional downside of rigid alignment techniques are difficultieswith dynamic misalignments that occur naturally during motion. As theuser moves, their soft tissue deflects while the solid structure aroundthem does not. This difference in positioning creates dynamicmisalignments that decrease exoskeleton efficiency and increase userdiscomfort.

A solution to this problem is to design an exoskeleton fixturing devicethat has additional degrees of freedom that maintain stiffness in thedirection of actuation, yet allows for flexibility in other directions.If rigidity in the direction of action is not maintained, theexoskeleton will not transmit force to the user efficiently. If theintended range of device motion is too rigid, it will inhibit naturaluser motion. An added refinement of this design is accommodating andemulating the multiple degrees of freedom experienced during naturalmovement with a device rigidly affixed to the body. While the humansystem has multiple compact joints with multiple degree of freedom,creating a mechanical analog increases mechanical complexity and devicefootprint.

It is ideal to have an exoskeleton mounting solution that minimizesweight, since added weight decreases the effectiveness of theaugmentation. It is also ideal to accommodate dynamic changes in jointalignment, while ensuring the user can easily adjust the device topersonalize fit. An additional favorable design consideration would beto have a system that is able to align itself properly, even when theuser dons it incorrectly.

It is ideal for the system to accommodate the multiple degrees offreedom that human joints accomplish. Any decrease in user range ofmotion reduces device efficacy and user satisfaction. Therefore, it isfavorable to undertake the complexities involved in multiple joints andmultiple degrees of freedom, even though adding mechanical degrees offreedom inherently adds failure points to the design and potentiallyreduces the overall robustness of the device. Additionally, any decreasein system robustness decreases reliability and decreases the use casesfor the exoskeleton.

SUMMARY OF THE INVENTION

The present invention provides new advantages not found in currentlyavailable exoskeleton devices. The current invention additionallyovercomes many disadvantages of currently available exoskeletonsemploying rigid structures close to the body.

In one exemplary embodiment, the invention is generally directed to thenovel and unique exoskeleton mounting designs that address the problemsassociated with user comfort, restricting user range of motion, and usercompatibility. The present mechanical system can allow an exoskeletondevice to attach to a user and dynamically align to the user's naturaljoint axis. Such a device can work on single or multi DOF joints andprovides for fixation adjustments by the user.

It is therefore an object of the present invention to provide a new andnovel exoskeleton mounting device that is adjustable and does notinhibit the user's expected range of motion. The current invention isintended to address the problems associated with the prior art ofexoskeleton devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features which are characteristic of the present invention areset forth in the appended claims. However, the invention's preferredembodiments, together with further objects and attendant advantages,will be best understood by reference to the following detaileddescription taken in connection with the accompanying drawings in which:

FIG. 1 shows a right side elevational view of an exoskeleton mountingdevice;

FIG. 2 shows a right side elevational view of the exoskeleton mountingdevice of FIG. 1 being adjusted;

FIG. 3 shows a right side elevational view of the exoskeleton mountingdevice of FIG. 1;

FIG. 4 front view of the mounting device of FIG. 1;

FIGS. 5A-5C are partial left side views of the mounting device of FIG. 1being rotated about a single first axis;

FIGS. 6A-6C are partial left side views of the mounting device of FIG. 1being rotated about a single second axis;

FIGS. 7A-7C are partial front side views of the mounting device of FIG.1 being rotated about a single third axis;

FIGS. 8A-8C are partial rear side views of the mounting device of FIG. 1being rotated about the first and second axes to keep the mounting padnormal to the front plane; and

FIG. 9 shows a left side view of the present invention with the samemovement as FIGS. 8A-8C.

DETAILED DESCRIPTION OF THE INVENTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the device and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those skilled in the art will understand that the devices andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the present invention is defined solely by the claims. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the present disclosure. Further, in the present disclosure,like-numbered components of the embodiments generally have similarfeatures, and thus within a particular embodiment each feature of eachlike-numbered component is not necessarily fully elaborated upon.Additionally, to the extent that linear or circular dimensions are usedin the description of the disclosed systems, devices, and methods, suchdimensions are not intended to limit the types of shapes that can beused in conjunction with such systems, devices, and methods. A personskilled in the art will recognize that an equivalent to such linear andcircular dimensions can easily be determined for any geometric shape.Further, to the extent that directional terms like proximal, distal,top, bottom, up, or down are used, they are not intended to limit thesystems, devices, and methods disclosed herein. A person skilled in theart will recognize that these terms are merely relative to the systemand device being discussed and are not universal. Further, for ease ofdiscussion, the present invention is discussed in connection with alower limb exoskeleton but the invention is also related and applicableto any exoskeleton.

In general, an embodiment of a novel exoskeleton is shown in FIGS. 1-9.The embodiment of FIGS. 1-9 shows a novel attachment mechanism having alinkage assemble which permits a pad face to maintain a substantiallyfixed linear distance from, for example, a shoe which the exoskeleton isattached. Through rotational movement of the linkage assembly, the padface can transmit forces from the exoskeleton to the appendage of theuser without applying any shear forces between the pad face and theappendage. The removal, or substantial minimization, of shear forces canreduce injuries to the user and minimize a source of inefficiency in theexoskeleton. The device can generally include a clamping member whichcan be slidably secured to a structural member. The clamping member caninclude a swing or support arm which is able, at a first end, to rotateabout a single axis which may be normal to a face of the structuralmember. The support arm can be generally “L” shaped such that theshorter portion can be secured to the clamp and the longer perpendicularportion can be secured to a pad. At the second end of the support arm,the pad can be pivotally fixed. The pad can be configured to pivot abouta first axis of rotation, which can be substantially parallel to thesingle axis, and a second axis which is perpendicular to both the firstand second axes and normal to a face of the pad. In some embodiments,the pad can further include a fixturing mechanism to secure the pad tothe user.

Referring to FIG. 1 of the mechanism, the current invention is shown ina general summary view alongside its application to an existing novelexoskeleton 1. Such an exoskeleton can be the exoskeleton disclosed inU.S. application Ser. No. 15/782,306, entitled “Unidirectional ActuatedExoskeleton Device,” filed Oct. 12, 2017, incorporated herein in itsentirety. The primary rotational axis 6 of the exoskeleton 1 can becoupled to the secondary rotational axis 5 to provide the multiplerotational degrees of freedom alongside the target ankle joint. The mainsolid member, or upright, 8 can be fixed to this primary rotational axis6 to provide the primary parallel structure of the exoskeleton 1 alongthe user's appendage.

Referring to FIG. 2, the primary fixturing, support bracket, or clamp, 3of the invention 11 can selectively float, or be height adjustable, onthe structural member 8 of the exoskeleton. The assembly 11 can freelyslide or shift longitudinally along the structural member 8 until it isfixed in place at an appropriate height for the user. In an alternativeembodiment, the primary fixturing 3 can be a support bracket that isrigidly affixed to the structural member 8 of the exoskeleton such thatthe primary fixturing 3 is fixed with respect to the structural member8. When the assembly 11 is at the desired height, a clamping mechanism 3can be applied to fix the assembly 11 relative to the structural member8. For example, the clamping mechanism can be clamped via clamping screw4, as shown in FIG. 2. In alternative embodiments the clamping mechanism3 can be any mechanical, electrical, magnetic, or chemical fixationmeans that are strong enough to transmit the necessary forces from theexoskeleton 1 to the user. This arrangement can allow for the user toadjust the exoskeleton 1 to improve alignment for efficiency andcomfort. In one embodiment, the user can adjust the fixture until thecushioned pad 7 is proximal to the widest part of the target bodysegment, for example the shin of the user. In alternative embodiments,the cushioned pad 7 can be adjusted to any desired location along a userof the device 1. In some embodiments, additional care may be taken toensure the top surface of the support arm 13 is perpendicular to the padface 7.

Referring to FIGS. 3 and 4, the support arm 13 of the assembly 11 can berotatable about a first axis of rotation 9 to place the padded guardsurface 7 against the user's body. The primary fixturing clamp 3 can beattached to the support arm 13 through the use of one or more rotarybearings, a pin joint, and/or one or more bushings. The pad 7 can berotatably secured to the support arm 13 about, at least, a second axisof rotation 10 to comfortably seat the pad 7 flush against the body. Thesecond axis of rotation 10 can be parallel to and offset from the firstaxis of rotation 9. The support arm 13 and the pad can be connectedtogether with one or more rotary bearings, one or more pin joints,and/or one or more bushings. The pad 7 can be kept rigid against thebody segment using an additional fixturing mechanism 14. The fixturingmechanism 14 can be a strap, but can be a magnetic clasp, ratchetingbelt, or other soft adjustable tension element wrapping or binding thedevice to the leg. With the strap 14 securing the device 11 to the user,a non-parallel rotational degree of freedom 12 can ensure the mountingface of the pad 7 is flush against the body.

Referring to FIGS. 5A-C and 6A-C, the first axis of rotation 9 and thesecond axis of rotation 10 are shown normal to the parallel rotationalaxis. FIGS. 5A-C illustrate one of the major mounting adjustments of thesupport arm 13, that are possible with the inclusion of the first axisof rotation 9, relative to the structural member 8. The degree offreedom of the support arm 13 about the first axis of rotation 9 alonewill result in the transfer of shear forces to the user at the top andbottom of the pad 7. The inclusion of the second axis of rotation 9between the pad 7 and the support arm 13 can reduces shear forcesapplied to the user's body by translating the possible shear into aself-centering force to maintain parallelism. As the shear force isnaturally encountered from the movements illustrated in FIGS. 5A-C onthe top and bottom faces of the pad 7, the second axis of rotation 10maintains the parallelism between the pad 7 and user, as seen in phantomin at least FIG. 9.

Referring to FIGS. 7A-C, with the novel implementation of multipleparallel axes 9, 10 and an additional non-parallel rotational axis 12,the mating surface of the pad 7 can, advantageously, center itself onthe user's body. In some embodiments, the mounting pad 7 can have anergonomic concave shape which can be complementary to the convex shapeof the user's target body segment. The pad 7 can find its center,relative to the user's body, automatically as it is tightened to thebody due to the complementary shape. As depicted in FIGS. 7A-C, the pad7 can be allowed to rotate about the non-parallel third axis of rotation12 while being adjusted. The concave shape of the mounting pad 7 coupledwith a rotational degree of freedom at the target human joint 6 canconstrain the exoskeleton structural member 8 to maintain parallelismwith the user's skeletal system. Since the mounting hardware 14 willonly fixture normal to the line of action, the applied clamping forcecan constrain the second axis of rotation 10 to maintain parallelismwith the target body segment. The additional first axis of rotation 9constrains the exoskeleton to be parallel with the underlying skeletalsystem from its rotational degree of freedom. In some embodiments, thesupport arm 13 of the assembly 11 can include only the first axis ofrotation 9, the second axis of rotation 10 and the non-parallelrotational axis 12.

Referring to FIGS. 8A-C, the combination of three distinct rotationaldegrees of freedom, about three axes 9, 10, 12, can also increases theuser comfort by allowing for natural realignment of the assembly 11.During use, it is often the case that misalignment can occur. Thecombination of three degrees of rotational freedom can provide the mainstructural element 8 of the exoskeleton a constrained degree of travelalong the skeletal support, ensuring alignment without applying sheeringforces. This allows for contact to be kept between the mating faces ofthe exoskeleton and user, while still minimizing the skin shear thatwould occur with a static mounting point. This dynamic mounting point 11also helps to maintain the user's regular range of motion by moving withthe body rather than rigidly acting against it.

Referring to FIG. 9, efficient force transmission can occur throughmaintaining a combination linear and rotational degrees of freedom ofthe assembly 11 in reference to the anchor body part. A purelyrotational degree of freedom of the pad 7 would not keep the pad 7aligned to the body segment, creating a shearing effect under load asseen in FIGS. 6A-C. A strictly linear degree of freedom would not beideal since that would allow for sliding of the pad parallel to the boneonce in motion, for example the movement seen in FIG. 2. These issuescan be avoided in the present invention due to the shaft clamp fixturingmechanism 4. By tying two radial degrees of freedom together between thepad 7 and the support arm 13, the structural component of theexoskeleton is kept in parallel with the body as shown in FIG. 9. Insome embodiments, the connection between the pad 7 and the support arm13 can be confined to two, perpendicular, axis of rotation—without anyadditional degrees of freedom. Further, in such an embodiment, one ofthe two axis of rotation can be parallel to an axis of rotation of thesupport arm 13 at the opposite end, where the support arm 13 isrotationally mated to the clamp 3. While the clamp 3 can be linearlyadjusted along the support 8, the clamp is fixed relative to the supportduring use of the exoskeleton. Through this configuration, the mountingsystem 11 can allow for some fine movements to retain the user's rangeof motion and comfort, without compromising force transmission efficacy.

It will be appreciated by those skilled in the art that various changesand modifications can be made to the illustrated embodiments withoutdeparting from the spirit of the present disclosure. All suchmodifications and changes are intended to be covered by the appendedclaims.

What is claimed is:
 1. An attachment device for a biomechanicalexoskeleton, the attachment device comprising: a support bracketconfigured and arranged to be fixed to a support of an exoskeleton; asupport arm, having a first end and a second end, pivotally supported bythe support bracket about a first joint at the first end, wherein thefirst joint has one or more degrees of freedom; a fixation pad connectedto the second end of the support arm at a second joint; and wherein thesecond joint has two or more degrees of freedom.
 2. The attachmentdevice of claim 1, wherein the support bracket is a clamp and a clampingpin configured to fix the clamp relative to the exoskeleton.
 3. Theattachment device of claim 2, wherein the clamp is configured to slidealong the support bracket when the clamp is not fixed by the clampingpin.
 4. The attachment device of claim 1, wherein the fixation pad ispivotally connected to the second end of the support arm about thesecond axis and a third axis, and wherein the third axis isperpendicular to the second axis.
 5. The attachment device of claim 4,wherein fixation pad is constrained to only pivot about the second andthird axes relative to the support arm.
 6. The attachment device ofclaim 5, wherein the support arm is constrained to only rotate about thefirst axis relative to the support bracket.
 7. The attachment device ofclaim 1, wherein the support arm is constrained to only rotate about thefirst axis relative to the support bracket.
 8. The attachment device ofclaim 1, further comprising, an attachment strap having a first endfixed to the fixation pad and a second end releasably attached to thefixation pad.
 9. The attachment device of claim 1, wherein the fixationpad is configured to naturally realign relative to the user during use.10. The attachment device of claim 9, wherein the fixation pad isconfigured to maintain contact with the user without applying sheerforces.